Steered and driven axle-end assembly

ABSTRACT

A steered and driven axle-end assembly has a steering knuckle whose inside and outside halves are pivotal about an upright pivot axis. An axle extends into the inside knuckle half and is connected to the inner side of a universal joint whose outer side is connected to one end of a gear train whose other end is connected to a wheel support which is rotatable about a horizontal wheel axis on the outside knuckle half. A pair of roller bearings centered on the wheel axis are spaced axially apart therealong by a spacing which is equal to at most half of the axial distance through which the outside knuckle half extends into the wheel support. Thus the outside knuckle half and associated structure can pivot through a considerable angle relative to the inside knuckle half for minimum turning radius of a vehicle embodying the axle-end assembly.

FIELD OF THE INVENTION

The present invention relates to a steered and driven axle-end assembly.More particularly this invention concerns such an assembly used inheavy-duty, off-the-road, and construction equipment.

BACKGROUND OF THE INVENTION

A steered and driven axle-end assembly normally has a knuckle formed ofinside and outside knuckle halves pivotal relative to each other aboutan upright pivot axis, the inside knuckle half being mounted rigidly onthe frame of the vehicle.

An exle extends into the inside knuckle half and is connected there tothe inner side of a universal joint whose outer side is connected to awheel support that is rotatable about a horizontal wheel axis by meansof roller bearings that support it on the outer knuckle half. Thus it ispossible for the outside knuckle half to pivot with the wheel carried onthe wheel support relative to the inside half while rotary force isstill transmitted through the universal joint, which is normally of theconstant-speed type, to the wheel.

In heavy-duty construction equipment it is desirable to provide thewheel brake inboard of the wheel on the axle. This is made possible byproviding stepdown gearing between the outside joint half and therotatable wheel support. The axle therefore rotates at a considerablygreater angular rate than the wheel so that brakes suitable for highspeed and low torque can be employed, thereby saving considerableexpense. This type of arrangement also has the advantage that thebearings and the like that support the axle or drive shaft can also beof the high-speed low-torque type which is considerably cheaper tomanufacture and which has longer service life than the type adapted forlow-speed high-torque use.

The main disadvantage of these systems, however, is that they arerelatively bulky. The distance between the knuckle and the wheel isrelatively great so that quite a bit of mechanism is exposed under thevehicle at each wheel. In construction equipment this disadvantage isvery great in that this mechanism is exposed to damage from the roughterrain on which the vehicle rides.

Another considerable disadvantage of such an arrangement is that itsaxial length, measured along the horizontal wheel axis, is so great thatthe wheel can only be cramped through a relatively limited arc from oneend to the other of its travel about the upright pivot axis defined bythe knuckle. The turning radius for the vehicle is therefore relativelylarge, another disadvantage in construction equipment which mustnormally be as maneuverable as possible.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved steered and driven axle-end assembly.

Another object is to provide such an assembly which is of minimumdimensions so that it not only does not project axially inwardly fromthe wheel where it would be exposed and subject to damage, but alsoallows the wheel to be cramped greatly in either direction for a minimumturning radius.

SUMMARY OF THE INVENTION

These objects are attained according to the instant invention in anarrangement wherein the support distance, which is the distance alongthe axis between the intersections of the contact angles of the tworoller bearings carrying the wheel support on the outside knuckle half,is at least twice as large as the axial spacing between the center ofthe roller bearings that support the wheel support on the outer knucklehalf. As a result of this construction a relatively small turning radiusis possible for the vehicle embodying the inventive axle-end assembly. Arelatively large tractor, for example, having large front wheels canhave a substantially smaller turning radius with the axle-end assemblyaccording to this invention than has hitherto been possible. Furthermorealmost the entire assembly can fit within the axial boundaries of thewheel, so that it is well protected from harm, a considerable advantagein heavy-duty construction equipment.

Yet another advantage of the system according to this invention is that,due to its reduced axial length, the pivot axis defined by the knucklehalves is very close to the upright central wheel plane. In fact thisaxis crosses the plane radially within the periphery of the wheel,intersecting the ground outside the wheel's central plane. Steering easeis therefore greatly improved.

According to further features of this invention the gearing is planetarygearing and includes a ring gear fixed on the outside knuckle half, asun gear fixed on the outer side of the universal joint, at least oneplanet gear meshing with the sun and ring gears, and a planet-carrierpin carrying the planet gear and fixed on the wheel support. With such asystem the drive axle is coaxial with the wheel axis and the wheel hubcarries the planet-carrier pin. Normally several such planet gears andplanet-carrier pins are provided equiangularly surrounding the sun gearso that this sun gear need only be supported adjacent the outer side ofthe universal joint, the various planet gears automatically centeringit. Such a planetary-type stepdown transmission gives a considerablestepdown ratio while being extremely compact.

It is also within the scope of this invention to employ a portal-typearrangement wherein the axle axis lies well above the wheel axis formachinery such as a road grader or the like. In this arrangement thegearing includes a large-diameter driven gear fixed on the support andcentered on the wheel axis and a small-diameter drive gear which isfixed on the outer side of the universal joint. Although this drive gearcan mesh externally directly with the large gear, according to thisinvention it meshes with a pair of flanking gears which both mesh withthe large gear. Thus once again the small-diameter drive pinion isautomatically centered between the flanking gears so that heavy-dutybearings are not needed to support it. Furthermore a double stepdown isachieved with this type of arrangement in an extremely compact spacewithin the motor-vehicle wheel.

DESCRIPTION OF THE DRAWING

FIGS. 1 and 2 are vertical sections through axle-end assembliesaccording to to this invention; and

FIG. 3 is a schematic end view illustrating the system of FIG. 2.

SPECIFIC DESCRIPTION

As seen in FIG. 1 an axle 1 centered on an axis 1A extends into theinside half 20 of a knuckle joint 6 defining a pivot axis 26 and havingan outside knuckle half 24 supported on bearings 22 in this inner half20 for pivoting about the axis 26. The axle 1 has splines 8 interfittingwith splines 9 on one side 11 of a constant-speed universal joint 2having an outer side 13 provided with splines 15 interfitting withsplines 16 on a stub shaft 3 supported at its inner end on a bearing 17in the outside knuckle half 24. A wheel support 5 centered on a wheelaxis 5A is formed by a hub 4 and a plate 39 secured together bystud-type bolts 38 that also serve to secure the rim 42 of a wheelcarried by the wheel support 5 and having a tire 43. A cuff 18 isprovided between the shaft 1 and the outside half 13 for protecting thejoint 2 from dust.

Inclined cylindrical-roller bearings 40 and 41 having diameters D andhaving centers spaced apart by a distance A support the wheel support 5on the outside knuckle half 24 for rotation about the axis 5A. Thecontact angles of the bearings 40 and 41, which are arranged back toback, intersect the axis 5A at points spaced apart by a distance S equalto somewhat more than twice the spacing A, which itself is equal to atmost one-third of the diameter D.

Secured via bolts 33 to the outer face of the knuckle half 24 is a ringgear 32 meshing with three angularly equispaced planet gears 35 (onlyone visible in FIG. 1) carried on respective planets pins 36 seated inthe hub 4 which, therefore, constitutes a planet carrier. The stub shaft3 carries on its free outer end a sun gear 31 meshing with the planetgears 35 and forming therewith and with the gear 32 a planetary-geartransmission 30.

Thus the rotation of the axle 1 will be transmitted through the joint 2to the small-diameter sun gear 31 whence it will be transmitted to theplanet gears 35 that will, therefore, orbit about within the fixed ringgear 32, imparting a considerable stepdown to the rotation rate of theaxle 1. As a result of the above-described relationship between thedimensions A, D and S the axis 26 cuts the middle plane P of the wheel42, 43 carried on the support 5 above the ground level G so that at theground level the axis 26 is spaced outwardly from this plane P by adistance L. Extremely good handling is therefore obtained. FIG. 1 alsoshows how the universal joint 2, outer knuckle half 24, and wheelsupport 5 lie wholly within the vertical projection of the wheel 42, 43,that is within the axial boundaries of this wheel 42, 43.

In the arrangement of FIGS. 2 and 3 reference numerals identical tothose of FIG. 1 refer to functionally identical structure. In thisarrangement the axis 1A lies well above the axis 5A for use of thisarrangement in a road grader or the like wherein very high groundclearance is needed. This is achieved by mounting on the outer side ofthe universal joint 2 a small-diameter pinion 31' that is flanked by andmeshes with a pair of medium-diameter gears 70 and 71 in turn meshingwith a large-diameter driven gear 73 secured via bolts 74 to a massivehub 75. This hub 75 rides via the bearings 40 and 41 on a ring 81 is inturn secured via bolts 77 to an element 78 integral with the outerknuckle half 24. A wheel 79 is secured via bolts 80 to this wheel hub75.

As a result of this floating mounting of the pinion 31' between thegears 70 and 71 it need only be supported on one side at a relativelylight-duty bearing 17'. Nonetheless once the high-speed rotation of thegear 31' is stepped down by the gears 70 and 71 and the gear 73 theoutput torque for rotation of the wheel hub 75 about the axis 5A will beconsiderable.

We claim:
 1. A steered and driven axle-end assembly comprising:an insideknuckle half; an outside knuckle half pivotal on said inside half aboutan upright pivot axis; an axle extending into said inside knuckle half;a universal joint having an inner side connected in said inside knucklehalf to said axle and an outer side; a wheel support rotatable about ahorizontal wheel axis; a wheel mounted on said support and having aperiphery engageable with the ground and centered on a wheel planeperpendicular to said wheel axis, said pivot axis crossing said planeradially within said periphery; a pair of tapered-roller bearingscentered on said wheel axis and having centers spaced axially aparttherealong by a spacing equal to at most half of the axial distancebetween the intersections of their contact angles and said wheel axis,said roller bearings rotatably supporting said wheel support on saidouter knuckle half; and stepdown gearing connecting said outer side ofsaid universal joint to said wheel support for rotation of said wheelsupport and said wheel by said axle at a substantially lower rate thansaid axle, said universal joint, outside knuckle half, and wheel supportlying wholly within the vertical projection of said wheel, said gearingincluding:a large-diameter driven gear fixed on said support andcentered on said axis and a small-diameter drive gear fixed on saidouter side of said universal joint, and two further gears flanking saidsmall gear and both meshing with said small gear and with said largegear, whereby said small gear meshes via said further gears with saidlarge gear.